Should the order of definitions correspond to the order of declarations in header/source files?

Question

If my header looks like this:

class foo {

public:
    foo();
    ~foo();

    QString b();
    QString c();
    QString a();

    void setB(QString s);
    void setC(QString s);
    void setA(QString s);

private:
    QString m_B;
    QString m_C;
    QString m_A;
};

Should my source neccessarily correspond like this:

foo::foo() {...}
foo::~foo() {...}

QString foo::b() { return m_B; }
QString foo::c() { return m_C; }
QString foo::a() { return m_A; }

void foo::setB(QString s) { m_B = s; }
void foo::setC(QString s) { m_C = s; }
void foo::setA(QString s) { m_A = s; }

or something like this:

foo::foo() {...}
foo::~foo() {...}

QString foo::b() { return m_B; }
void foo::setB(QString s) { m_B = s; }

QString foo::c() { return m_C; }
void foo::setC(QString s) { m_C = s; }

QString foo::a() { return m_A; }
void foo::setA(QString s) { m_A = s; }

or something else entirely? Or perhaps I should be reorganizing my header differently?

Thanks!